化学链燃烧/气化过程中载氧体金属-晶格氧/分子氧与硫的交互作用机理研究

The ability of sulfur-resistance of oxygen carriers is the key factor affecting their suitability for chemical looping combustion/gasification application of high sulfur-containing fuels. In the process, there exists the interaction effect between sulfur and oxygen carrier particles. However, at present the interaction mechanism is not clear. It involves as follows: insufficient understanding of the competitive reaction mechanism of carbon as well as hydrogen components conversion and sulfur evolution; unclear rules of the formation and distribution of oxygen-carrier-sulfides; and the research on oxidation performance of oxygen-carrier-sulfides in air reactor is still in its start-up step. In the regard, this proposal focuses on the interaction mechanism between oxygen carriers and sulfur. It will investigate the binding mechanism H2S and oxygen carriers and its reaction kinetics, and establish the correlation between the phase transition of oxygen carriers and the evolution of H2S. This is to obtain the interaction relationship and dynamics between oxygen carriers and sulfur molecules. Further, starting from the micro-physical and chemical structure, the formation and distribution of oxygen-carrier-sulfides and its regeneration mechanism will be studied. The evolution law of micro-physical and chemical structure in the process of oxygen-carrier-sulfides formation and regeneration will be revealed. Finally, the mechanism model of oxygen-carrier-sulfides formation and oxidation reaction will be established. This research will provide theoretical support and scientific basis for the development of sulfur-resistant oxygen carrier materials.

载氧体耐硫性是影响其是否适合高硫燃料化学链燃烧/气化技术的关键。硫在化学链燃烧/气化过程中存在与载氧体的交互作用。然而，目前其交互作用机理并不清楚，具体体现在：对碳、氢组分迁移转化和硫演化的竞争反应机制的认识并不充分；载氧体硫化物生成和分布规律尚不明确；载氧体硫化物在空气反应器氧化性能的研究尚处于起步阶段。鉴于此，本项目聚焦于载氧体与硫的交互作用机理，研究H2S和载氧体的结合机理和反应动力学，建立载氧体相态转变与H2S演化之间的关联，获取载氧体与硫分子间的交互作用关系及动力学规律；从微观物化结构出发，研究载氧体硫化物生成和分布规律以及载氧体硫化物再生反应机理，揭示载氧体硫化反应及再生反应过程中微观物化结构的演变规律；建立载氧体硫化物生成及氧化反应机理模型。本项目的研究对发展具有耐硫性的载氧体材料提供理论支持和科学依据。

围绕项目的关键科学问题，采用先进的流化床热重分析仪，揭示了载氧体气固化学链反应机制和载氧体内组分演变规律；建立了化学链过程中耦合内外扩散、化学反应和焦炭颗粒孔隙结构演变规律的单颗粒焦炭动力学模型；研究并获得了石油焦化学链催化转化过程中C/H/S组分迁移规律。阐明了载氧体与硫的交互作用机制，发现了赤泥载氧体对石油焦中硫元素的原位固定功能。基于化学反应热力学、实验研究、化学反应动力学和量子化学，获得了硫分子和载氧体的气固反应特性，发展和建立了硫-载氧体气固反应动力学模型。首次提出了基于化学链原理的低温制硫和联产硫酸新技术路线，研究并获得了基于V2O5基载氧体的低温（<250℃）化学链硫逐级氧化机制；揭示了低温条件下的氧迁移和硫逐级转化的反应路径，发现了氧化条件下的载氧体催化硫氧化反应现象。项目发表SCI收录论文11篇；参加学术会议10次，获优秀口头报告奖、优秀论文奖和优秀墙报奖，共计3次；申请国家发明专利2件，授权实用新型专利1件；培养研究生6名。